Hot air furnace



Harry C.Lo11man LaCrosse,Wkconsin [21] AppLNo. 785,074

United States Patent [56] References Cited UNITED STATES PATENTS 2,313,933 3/1943 Goerg...........................

[72] Inventor 126/110X 126/119 126/110 126/110BX ted m'y gg 2,923,349 2/1960 MarbIeetaL... 3,105,485 10/1963 [731 Assgnee TheT'mcmpw 3,241,544 3/1966 Lohman.......................

La Crosse, Wisconsin Primary Examiner-Charles J. Myhre a corporation of Wisconsin Attorneys-Arthur 0. Andersen, Carl M. Lewis and Lee E.

Johnson [54] HOT AIR FURNACE 9 Claims, 6 Drawing Figs.

ABSTRACT: A hot air furnace having clamshell heat exchangers sealingly connected to a combustion products manifold by way of a ceramic fiber gasket interposed and secured between rims of the heat exchanger outlets and rims at the manifold inlets.

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INVENIOR. HARRY C. LOHMAN ATTORNEY PATENTEDBtB mu 3345424 SHEET 2 BF 2 INVENTOR. HARRY C. LOHMAN ATTORNEY clamshell heat exchanger and a s1 HOTAIRFURNACE Heretofore, it has been common practice to construct furnace heat exchangers and. particularly gas furnace :heat exchangers from two substantially allochiral shells of generally planar configuration. The shells are secured to each other at their rims with their concave sides in face-to-face relationship thereby forming a combustion chamber and combustion products passage ftherebetween. A gas burner is located at the which extends around the rims of the shells except in those areas where the rims are so spaced to provide an opening to the interior of the clamshell heat exchanger. The flanges of one shellare normally sealingly secured to thefl anges of the other shell be a pressure resistance welding, as for example,

spotwelding. j I j While the aforementioned interface flangeshave provided a reliable way of sealingly joininga pair of shells for operation at combustion temperatures, they are not useful for and they generally interfere with constructing a sealed connection between the heat exchanger combustion products opening and the combustion products manifold. Because of the difficulty in making a sealed connection at this point, it has been common practice tofflame or are weld these members in the vicinity of this joint. This welded joint between the heat exchanger outlet opening and the combustion products manifold when constr'ucted in this manner is extremely costly and time consuming to make.

Now with reference to the drawingsJt will be seen that a gas fired, hotair .fumace .10 is -shown as having a casing 12 of generally rectangular configuration having a front wall 14, a

It is therefore a principal object of my invention to provide a fluid fuel fired air heater having a plurality of clamshell heat exchangers which has a lower manufacturing cost.

It is a particular object of this invention to provide a low cost and durable sealed connection between a plurality of clamshell. heat exchangers and a combustion products manifold.

And it is still another object of my invention to provide a sealed jointbetween a hot air furnace combustion products manifold and the combustion products outlets of a plurality of clamshellheat exchangers ,which may be made quicklyand simply with a minimum of equipment.

Andstill a further object of thisinventionis to provide a strongsealed connection which may be madesimultaneously between a combustion products manifold and the outlets of a plurality of clamshell heat exchangers. v H i Other objects and advantages will become apparent as this specification proceeds to describe the invention with reference to the accompanying drawings in which:

FIG. 1 is a side elevation of a gas fired unitair heater or furnace having an upper portion of the casing side thereof broken i away to show the upperportion of one of the clamshell heat exchangers therein and having a portion of one shell of said clamshell heat exchangerpartially broken away to show the joint between the clamshell heat exchanger combustion products outlet opening and the combustion products manifold; i

FIG. 2 is a vertical section taken atline2-2 of FIG. 1 showing'a rear end view of the clamshell heat exchangers and their outlet connections to. a panelrof the combustion products manifold; s

FIG. 31s an enlarged exploded perspective of the connection between the combustion products outlet opening of one panel of the combustion products manifold;

FIG. 4 is an enlarged view taken at lined-4 of FIG. 1 show:

ing a portion of the combustion products manifold panel; F1615 is a section takenflat line 5-5 of FIG. 4 showing a exchanger and the combustion products manifold panel; and

rear wall 16, a top wall 18, a bottom wall 20, and a pair of substantially parallel spaced sidewalls =22. A motor driven propeller fan 24 is disposed in a circular air intake aperture 26 in rear wall 16 for passing relatively cool air horizontally into casing 12. i i i i i Front wall 14 is provided with a rectangular hot air discharge aperture 281. A plurality of louvers 30 may be arranged in saiddischarge apertureto direct flow of heated air from the furnace or heater casing. j Disposed within casing 12 in parallel relation with sides 22 are a plurality of spaced generally rectangular and planar clamshell heat exchangers 32. Each clamshell heat exchanger 32is comprised of two allochiral concave-convex sheet metal shells 34 arranged withtheir'concave sides in face-to-face relationship. A major portion of the rims of the shells 34 are contiguous along an interface. Those contiguous portions of the rims are provided within interfacialflanges 36. The flanges 36 of each shell34 may be simply pressure. resistance welded at spots orthroughout their length to provide an adequate high-temperature seal. i i j The concave interior contour of shells 34 define therebetween a combustion chamber 38. A fluid fuel burner 40 is disposed within the lower portion of each of combustion chambers 38 as will be seen in FIGS. 1 and 2. Burners 40 may be appropriately manifolded as at 42 to a source of fuel gas.

The lower portion of each of heat exchangers 32 may be appropriately supported by baffle plate 44 connected to casing An elongated combustion products manifold 46disposed within and across the upper rear comer of casing 12 provides fluid communication between the combustion chambers 38of clamshell heat exchangers 32 and the furnace flue 48. Manifold 46 has for one of i its sides an elongated panel 50 which is provided with a row of apertures 52 and may be supported on casing 12 as at 54.

The rims of'shells 34 of each heat exchanger 32 are spaced for an interval at the upper rear corner thereof tojprovide a combustion products discharge opening 56 coincident with the interface of shells 34 for discharging combustion products from chamber 38 of the heat exchanger. The discharge opening 56 of each heat exchanger 32 isdisposed in alinement with 34 has a flange 58 of generally cylindrical configuration which extends through the plane of panel 50 at an aperture 52. Each Niagara Falls, New York, 14302, maybe used to construct shell 34 is further provided with a shoulder 60 at the base of flange 58 as clearly seen in FIGS. 3, 5, and The rim of each aperture 52 within sheet metal panel 50 is shaped to present a first shoulder 62 which overlies shoulders 60 of shells 34.

Shoulder 60 is somewhat widened at 6410 receive the ends of flanges 361A ceramic fiber gasket 66 is compressed between shoulders60 of shells 34 and shoulder 62 of panel 50. Gasket 66 may be provided. as a rectangular sheet having apertures formed therein in alinement with the apertures 52 of panel 50. Type 970-] ceramic fiber paper available from the Refractories Division of The Carborundum Company, P. O. Box 337,

gasket 66. Gasket 56 overlies the unwelded interface between each of shells 34 of a heat exchanger32 adjacent aperture 56 detail of one portion of the joint between. a clamshell heat t as at 68. So that gasket 66is tightly compressed over and seals the endsof flanges 36, panel 50 has been provided with a pair of inwardly extending embossments70'.

The rim of aperture 52 is further provided with an annular flange 72 of generally U-shapedcross section which receives the ends of heat exchanger flanges 58 within the bight thereof for locating each heat exchanger. 32 with respect to panel 50.

The end of theouter leg of flange 72 joins with shoulder 62 as clearly seen in FIGS. 3, 5, and 6. The terminal portion of the FIG. 6 is another section taken at line 6 -6'of FIG. showing "another detail ofthe joint betweenaclamshell. heat exchanger 'and'the combustion products manifold panel.

inner leg of flange 72 is provided with tabs 741(see FIGS. 1, 3, and 5) whichare swaged laterally of aperture 52. to tightly conform tothe underside of shoulder 60m seen in FIG. 5

thereby clinching shell shoulder 60 and gasket 66 between tabs 74 and shoulder 62 of panel 50. The swaging of tabs 74 into all of heat exchangers 32 may be accomplished simultaneously if desired. However, if production does not warrant such speed, the heat exchangers 32 may be individually connected to panel 50 and successively swaged in place. The above described construction provides an efficient, low cost sealing and connecting means between clamshell heat exchangers and their associated combustion products manifold which connection is able to withstand the high-temperature associated with these portions of a furnace.

Having now described in detail the preferred embodiment of my invention, I contemplate that many changes may be made without departing from the scope or spirit thereof, and I desire to be limited only by the following claims.

I claim:

1. In a hot air furnace having a casing, a discharge manifold within said casing for collecting the products of combustion from a plurality of heat exchangers and directing said products of combustion to a flue, said discharge manifold including a panel having a plurality of apertures therein, a plurality of clamshell heat exchangers disposed on one side of said panel, each of said clamshell heat exchangers having first and second concave-convex sheet metal shells, said shells being disposed with their'predominantly concave sides in face-to-face relationship thereby defining a combustion chamber therebetween, and sealing means for sealingly connecting a major portion of the rims of said first and second shells, a minor portion of the rim of each of said first and second shells being spaced from the other shell to thereby define a combustion products discharge opening therebetween, the improvement comprising: a first flange extending outwardly from one of said clamshell heat exchangers along the rim of said discharge opening therein and extending through one of said apertures; a shoulder at the base of said flange; a gasket compressed between said shoulder and the rim of said aperture; a second flange on the rim of said aperture having a first portion extending from said panel away from said heat exchanger; a second portion extending from said first portion over the ends of said first flanges, a third portion extending from said second portion toward and into the discharge opening of said heat exchanger, and a fourth portion extending from said third portion laterally of said opening underneath said shoulder thereby mechanically securing and sealing said heat exchanger to said panel at its discharge opening.

2. A hot air furnace comprising: a casing; a discharge manifold means within said casing for collecting products of combustion from a plurality of heat exchangers and directing said products of combustion to a flue; said discharge manifold including a panel having a plurality of apertures therein; a plurality of clamshell heat exchangers disposed on one side of said panel; each of said clamshell heat exchangers having first and second concave-convex sheet metal shells; said shells being disposed with their predominantly concave sides in faceto-face relationship thereby defining a combustion chamber therebetween; each of said sheet metal shells having an outer rim integral therewith; sealing means for sealingly connecting a major portion of the rims of said first and second shells; a minor portion of each of said rims of each of said first and second shells being spaced from the rim of the other shell to thereby define a combustion products discharge opening therebetween; each of said discharge openings being in alinement with one of said apertures; a gasket means compressed directly between said shells and said panel at the rims of said discharge opening and the rim of said aperture for providing a high-temperature seal between said heat exchangers and said discharge manifold; and means securing each of said heat exchangers to said panel at their discharge openings.

3. The apparatus as defined by claim 2 wherein said gasket means is a single gasket traversing a plurality of said clamshell heat exchangers adjacent the discharge openings thereof.

4. The apparatus as defined by claim 2 including: a flange on each of said shells extending from saidclamshell heat exchanger along the rim of its discharge opening; and a panel flange extending along the rim of an aperture in said panel; one of said flanges being generally U-shaped in its cross section and receiving the other flange within the bight thereof.

5. The apparatus as defined by claim 2 wherein said rim of each of said discharge openings includes a shoulder upon which rests said gasket means.

6. The apparatus as defined by claim 5 wherein said sealing means includes a flange extending along said major portion of the rims of said shells and terminating substantially at a plane coplanar with said shoulder whereby said gasket means resting on said shoulder seals the interface of said shells at the end of said flange.

7. The apparatus as defined by claim 5 wherein the rim of each of said apertures includes a second shoulder for constraining that portion of said gasket means supported by said shoulder of said shells.

8. The apparatus as defined by claim 5 including tab means on the rim of said apertures extending through said discharge 

